PHP_数据库_PDO查询操作和预编译语句操作。

PDO使用dns进行连接，我采用new ClassName()方式（其实大同小异，形式罢了）。

尝试先插入，然后查询，在查询遍历每一条的时候插入。
结果很简单，第一次插入能插入，但是在遍历结束之前是不能插入的。

<?php
$dsn = 'mysql:dbname=stuphp;host=127.0.0.1';
$user = 'root';
$password = 'admin';

try {
    $dbh = new PDO ( $dsn, $user, $password );
} catch ( PDOException $e ) {
    echo 'Connection failed: ' . $e->getMessage ();
}
$dbh->query ( 'set names utf8' ); // 是我的mysql数据库也是utf8编码的 。但是就是不行。必须这么写才行。

//插入一条记录
$username = 'leaves';
$password = 's&^*&B324';
$mark = '我是好人';
$pstmt = $dbh->prepare ( 'INSERT INTO TUSER(USERNAME,PASSWORD,MARK) VALUES(:username,:password,:mark)' );
$pstmt->bindParam ( ':username', $username );
$pstmt->bindParam ( ':password', $password );
$pstmt->bindParam ( ':mark', $mark );
$pstmt->execute ();
print_r ( $pstmt->errorInfo () );

$sql = 'SELECT USERNAME,PASSWORD,MARK FROM TUSER';
$result = $dbh->query ( $sql );

$row = $result->fetchObject ();
$dbh->beginTransaction();
while ( $row ) {
    $username = $row->USERNAME;
    $password = $row->PASSWORD;
    $mark = $row->MARK;
    
    echo $username . "\t";
    echo $password . "\t";
    echo $mark . "<br/>";
    
    
    //------------------中途尝试插入
    $pstmt = $dbh->prepare ( 'INSERT INTO TU22SER(USERNAME,PASSWORD,MARK) VALUES(:username,:password,:mark)' );
    $pstmt->bindParam ( ':username', $username );
    $pstmt->bindParam ( ':password', $password );
    $pstmt->bindParam ( ':mark', $mark );
    $pstmt->execute ();
    print_r ( $pstmt->errorInfo () );
    //上面的查询不会成功。原因是在查询没有结束的时候不允许你继续插入，就好像别人在存钱，你在取钱一样。
    //下面是异常信息
    /*
     * Array ( [0] => HY000 [1] => 2014 [2] => Cannot execute queries while
     * other unbuffered queries are active. Consider using
     * PDOStatement::fetchAll(). Alternatively, if your code is only ever going
     * to run against mysql, you may enable query buffering by setting the
     * PDO_MYSQL_ATTR_USE_BUFFERED_QUERY attribute. )
     */
    
    $row = $result->fetchObject ();
}


//插入一条记录,下面的代码能执行，无错
// $username = 'leaves';
// $password = 's&^*&B324';
// $mark = '我是好人';
// $pstmt = $dbh->prepare ( 'INSERT INTO TUSER(USERNAME,PASSWORD,MARK) VALUES(:username,:password,:mark)' );
// $pstmt->bindParam ( ':username', $username );
// $pstmt->bindParam ( ':password', $password );
// $pstmt->bindParam ( ':mark', $mark );
// $pstmt->execute ();
// print_r ( $pstmt->errorInfo () );
?>